The present invention relates to presser feet for sewing machines and, in particular, to a presser foot for traversing a raised area without collateral noise and a loss of forward stitching speed.
Sewing machines are generally provided with presser feet for holding the sewn material as the sewing needle is withdrawn. The presser foot is attached to a presser bar, which moves in alternate phase opposition to the needle carried by a needle bar. The foregoing arrangement works highly satisfactory in most instances. Difficulties, however, are presented when traversing raised areas wherein a cross panel is present, oftentimes referred to as a high seam. Generally, the presser foot will not ride over the raised area requiring interruption of the sewing, manually raising the presser bar to clear the raised area, stitching slowly thereacross, lowering the presser bar, and resuming normal stitching thereafter. In addition to the loss in sewing productivity, the raised presser bar during this period generates considerable undesirable noise.
Efforts have been made to overcome some of the above limitations including provisions for automatically raising the presser foot as disclosed in U.S. Pat. No. 5,899,157 to Kurono et al. Other provisions have been made as disclosed in U.S. Pat. No. 5,590,614 to Murata et al for preventing operation if the presser foot is not adequately cushioned. Additional presser foot control is disclosed in U.S. Pat. No. 5,718,182 to Nakayama et al. wherein a downwardly biased presser foot contacts the material during operation. The pivot axis is aligned with the presser bar and resent problems in high seam applications inasmuch as the reciprocating presser foot in the downward position engages the raised panel and precludes continued movement. Moreover, the trailing surface of the presser foot abruptly leaves the raised area and may create stitching discontinuities.
In view of the foregoing, it would be desirable to provide a presser foot for use in high seam applications wherein the foot freely advances over a raised area maintaining normal stitching speed and continuous affirmative contact with the material.
The foregoing objectives are accomplished in the present invention by a presser foot having a pair of spring biased pressure shoes having inclined leading and trailing ramped surfaces forward of the presser bar that allow the shoes to traverse and conform to a high seam area while maintaining continuous contact with the material. The shoes have a center horizontal lower presser surface for normal engagement with the material. As the leading surface engages the raised area, the shoes are reversely pivoted against spring biasing to conform to the material elevations. The shoes are normally biased to the horizontal position for traversing the raised area and reversely downwardly pivoted to bridge the material elevations upon exiting the raised area. By locating the shoes forward of the presser bar, continuous tracking with the material is achieved. Resultant, sewing speed may be maintained and the continuous pressure against the material reduces the noise attendant conventional raised presser foot positioning.
Accordingly, it is an object of the present invention to provide a presser foot for high seam sewing that allows sewing speeds to maintained without interruption for repositioning the presser foot.
Another object of the invention is to provide a presser foot that maintains continuous contact with the sewn material while traversing raised stitching area thereby eliminating collateral noise.
A further object of the invention is to provide a presser foot for a sewing machine having inclined leading and trailing surfaces forward of the presser bar that conform to changes in sewing elevations without requiring a slowing of stitching speed or presser foot repositioning.